An investigation into the vehicle abnormal sound caused by combustion noise of a gasoline engine

作者：Liu Ruijun; Hao Zhiyong; Yan Yongjia; Ma Junda; Zheng Xu; Luo Le

来源：Qiche Gongcheng/automotive Engineering, 2016, 38(10): 1252-1257 and 1263.

• Abnormal sounds
• Acceleration process
• Cylinder pressures
• Engine compartments
• Generalized S transform
• In-cylinder pressures
• Naturally aspirated
• Time frequency analysis

Troubleshooting and diagnosis are proceeded on the abnormal sound appearing at tip-out moment in the acceleration process of a SUV with a 1.5L naturally aspirated gasoline engine in this paper. Firstly, the abnormal sound is reconstructed by the bench test of powertrain to exclude the suspicion on car body as noise source. Then the sound intensity of engine and the NVH of other parts are measured on dynamometer, the abnormal sound signals in engine compartment are ascertained by filtering and audio playback to be at a frequency band of 6-8kHz, and are confirmed to be diffuse sound source and accord with the features of combustion noise by the sound intensity test on all end planes of engine. Furthermore, the adaptive generalized S transform is performed on cylinder pressure and vibration and noise signals. The results show that there are abnormal excitation of 6-8kHz in cylinder pressure as well, which agree well with abnormal sound in time domain. For further confirming the source of noise, the ECU ignition advanced angle map is adjusted at tip-out moment. As a result, the variation amplitude of ignition timing reduces, cylinder pressure steadily falls, the abnormal sound by subjective judgment disappears and the cylinder pressure excitation of 6-8kHz in time-frequency chart obviously weakens. Finally it is found by magnifying cylinder pressure-crank angle curve that the moment the cylinder pressure excitation of 6-8kHz appears corresponds to the rippled second peak after TDC, caused by trace knock possibly.

• 出版日期2016
• 单位浙江大学